Poly(arylene ether ketone)s with pendant, monodisperse oligobenzamide and oligobenzoate side chains facilitated a study of the effect of hydrogen bonding on chain interactions. A stepwise condensation reaction between acid chlorides and amine or alcohol functions was used to synthesize new series of carboxy-terminated oligobenzamides and oligobenzoates. These oligomers as well as benzoyl chloride were then reacted with two isomeric amino-functionalized poly(arylene ether ketone)s, to lead to modified polymers 10-13. The polymers were charaterized by H-1 NMR, C-13 NMR, and IR spectroscopy and gel permeation chromatography. The influences of the length and chemical nature of the side chain on the thermal and mechanical properties were studied. The transformed polymers showed different thermal and mechanical behavior, depending on the length and chemical nature of the side chain. Polymers with pendant oligobenzoates, for example, had lower T(g)s and Young＇s modulus in comparison to the respective polymers with oligobenzamide side chains. These results establish the considerable importance of hydrogen bonding on the improvement of the polymer properties.